How to style child components from parent component's CSS file?

Issue

I've got a parent component:

<parent></parent>

And I want to populate this group with child components:

<parent>
  <child></child>
  <child></child>
  <child></child>
</parent>

Parent template:

<div class="parent">
  <!-- Children goes here -->
  <ng-content></ng-content>
</div>

Child template:

<div class="child">Test</div>

Since parent and child are two separate components, their styles are locked to their own scope.

In my parent component I tried doing:

.parent .child {
  // Styles for child
}

But the .child styles are not getting applied to the child components.

I tried using styleUrls to include the parent's stylesheet into child component to solve the scope issue:

// child.component.ts
styleUrls: [
  './parent.component.css',
  './child.component.css',
]

But that didn't help, also tried the other way by fetching the child stylesheet into parent but that didn't help either.

So how do you style child components that are included into a parent component?

Solution

Update - Newest Way

Don't do it, if you can avoid it. As Devon Sans points out in the comments: This feature will most likely be deprecated.

#Update - Newer Way From Angular 4.3.0, all piercing css combinators were deprecated. Angular team introduced a new combinator ::ng-deep (still it is experimental and not the full and final way) as shown below,

DEMO : https://plnkr.co/edit/RBJIszu14o4svHLQt563?p=preview

styles: [
    `
     :host { color: red; }
     
     :host ::ng-deep parent {
       color:blue;
     }
     :host ::ng-deep child{
       color:orange;
     }
     :host ::ng-deep child.class1 {
       color:yellow;
     }
     :host ::ng-deep child.class2{
       color:pink;
     }
    `
],



template: `
      Angular2                                //red
      <parent>                                //blue
          <child></child>                     //orange
          <child class="class1"></child>      //yellow
          <child class="class2"></child>      //pink
      </parent>      
    `

---

# Old way

You can use encapsulation mode and/or piercing CSS combinators >>>, /deep/ and ::shadow

working example : http://plnkr.co/edit/1RBDGQ?p=preview

styles: [
    `
     :host { color: red; }
     :host >>> parent {
       color:blue;
     }
     :host >>> child{
       color:orange;
     }
     :host >>> child.class1 {
       color:yellow;
     }
     :host >>> child.class2{
       color:pink;
     }
    `
    ],

template: `
  Angular2                                //red
  <parent>                                //blue
      <child></child>                     //orange
      <child class="class1"></child>      //yellow
      <child class="class2"></child>      //pink
  </parent>      
`

Answered By - micronyks